Electric generator



F. J. WHITCOIMB.

ELECTRIC GENERATOR.

APPLICATION FILED APR.3, 1919.

Patented Apr. 20, 1920.

2 SHEETSSHEET 1.

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UNITED STATES PATENT OFFICE.

FRED J WHITCOMB, OF CLEVELAND, OHIO, ASSIGNOR TO THE TEAGLE COMPANY, OF

CLEVELAND, OHIO, A CORPORATION OF OHIO.

ELECTRIC GENERATOR.

Application filed April 3, 1919.

To all whom it may concern Be it known that I, FRED J. WHITCOMB, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Electric Generators, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to improvements in electric generators and has to do more especially with improvements in the frame work of electric generators having built up frames or field structures. In its broader aspects the invention is not limited to any particular form or type of generator but it has been developed, and in some of its aspects is peculiarly advantageous, in connection with magnetov generators of the type illustrated in the accompanying drawln s.

One of the objects of the invention is t e provision of an improved built up frame structure for electric generators whereby proper running clearance can be maintained between the rotor and the polar faces of the stator.

Another object of the invention is the provision of an improved mounting for the permanent magnets of magnetos.

Another object of the invention is the provision of a magneto in which the means for securing the magnets to the pole pieces serves also to maintain the running clearance between the stator and the rotor parts.

The manner in which the foregoing objects are attained will be pointed out in the following description in connection with the accompanying drawings in which I show my improvements embodied in a magneto of the inductor alternator type.

In the drawings,

Figure 1 is a side elevation of the magneto. v

Fig. 2 is a left end elevation of the same.

Fig. 3 is a right end elevation of the same. FFig. 4 is a section on the line IV-JV,

Fi 5 is a fragmentary section on the line V ,Fig. 3.

Referring in detail to the construction illustrated, 2 indicates a combined base and pole piece of soft iron having a polar face 2, and 3 is an upper pole piece of soft iron which is united to the base by non-magnetic end plates at and 5. The pole pieces 2 Specification of Letters Patent.

Patented Apr. 20, 1920.

Serial No. 287,105.

and 3 and the end plates 4 and 5 are rigidly secured together by screws 6 and dowel pins 7 and thus constitute a rigid rectangular frame. The pole piece 3, which is preferably cored out as indicated to avoid superfluous metal, has laminated pole extensions 8 and 9 with polar faces 8 and 9*, respectively. These pole extensions are preferably formed by a series of soft iron laminae 10 which are rigidly united by rivets 11. The pole piece 3 is formed with depending under-cut flanges or extensions 3* and the laminae 10 are correspondingly notched to enter between said flanges with a driven fit and form a tight and rigid dove-tailed connection between the parts.

12 indicates as an entirety an inductor rotor mounted to turn about the longitudinal axis of the polar faces 2 8 and 9. The rotor comprises a shaft section 13 and a laminated soft iron flux distributing section 14 keyed upon the shaft and rigidly held between. end plates 15 and 16, the plate 15 bearing against a shoulder on the shaft 13 while the plate 16 is secured in position by a pin 17. The rotor is operatively mounted in suitable anti-friction bearings 18 and 19 which are mounted respectively in the end plates 4 and 5.

On pole extension 8 is mounted a high tension winding 20 of any suitable construction and a condenser 21 may conveniently be mounted as shown on the pole extension 9. A casing 22 incloses a breaker mechanism of any suitable construction actuated in the usual manner by the rotor shaft, and above the breaker is a suitable distributer mechanism 23 constructed and actuated in the usual manner. The detailed construction of the electrical windings, the condenser, breaker and distributer are not shown and described as any suitable form of these parts may be employed in connection with my invention.

The field excitation of the generator is 1 furnished by permanent magnets 2d, 24; of straight bar form, there bein in the construction shown two pairs of t ese magnets. The magnets have their poles of one polarity in contact with the bottom pole piece 2 and their opposite poles in contact with the upper pole piece The bottom pole 2 has its sides planed off at 2", 2 and the upper pole piece has its sides similarly planed at 3", 3 to nicely fit the accurately ground lateral surfaces of the ends of the magnets and insure good magnetic joints. Adjacent the magnet engaging faces 2 the pole piece 2 is formed with under-cut shoulders 2, 2 to support the lower ends of the magnets which are beveled to fit the upper under-cut sides of the said shoulders. The upper pole piece 3 is formed adjacent its magnet ena in faces-3 3 with outwardl extending flanges 3", 3 which overlie the upper ends of the magnets. The upper ends of the magnets also are beveled as indicated and each is engaged by a vertically arranged set screw 25 mounted in the adjacent flange 3. \Vith this construction the tightening of the set screws 25 exerts a longitudinal thrust in the magnets 24 and by reason of the beveled ends of the magnets in engagement with the shoulders 2 and the screws 25, the thrust is accompanied by lateral pressure of the magnets against the faces Q 'and 3 In generators of the type illustrated, as invented by Leon J. Le Pontois, the permanent magnets, prior to my invention were secured to the pole pieces by screws passing through the magnets into the pole pieces, each magnet being drilled at each end to receive such a screw so that with four mag nets eight securing screws were required. This prior construction was expensive because of the amount of machine work involved. Furthermore, it was found that when the generators were secured in operative position by being strapped down to their supports the tension in the securing straps tended to force the upper pole piece toward the lower pole piece and thus interfered with the running clearance between the rotor and the cooperating polar faces of the stator. Of course, the result would be the same if any heavy weight were mounted on the generator. This tendency to interference of the parts was increased by the fact that the end plates 4 and 5 are ordinarily die cast from relatively soft materials so that ressure exerted through the screws 6 and owel pins 7 tended to enlarge the holes in the end plates with resultant play of the parts.

It will readily be seen that my improved method of securing the permanent magnets overcomes both of the above mentioned difficulties attaching to the prior forms of con struction. In the first place, each magnet is very effectively secured in close magnetic contact with the pole pieces by means of a single set screw, the drilling of two holes in each magnet with consequent reduction in its cross section is entirely eliminated and instead of the drilling and tapping of two holes in the pole pieces 2 and 3 it is only necessary to drill and tap a single hole in the flange 3. A suitable bevel can be given to the ends of the magnets by the same shearing operation that cuts them to desired length from straight bar stock. The saving both in machine work and materials is thus substantial. In the second place, my improved method of securing the magnets entirely overcomes interference with the running clearance between the stator and rotor parts because the magnets serve as heavy pillars between the base and the upper pole piece and when the set screws 25 are tightened to secure the magnets any movement of the upper pole piece toward the lower pole piece or base is positively prevented both because of the elimination of play between the shoulders 2 and the lower ends of the magnets and between the screws 25 and the upper ends of the magnets, and also because of the hardness of the materials of these parts. Thus, no matter what load is placed upon the top of the generator by the strap securing means or otherwise, the maintenance of the running clearances of the machine is insured.

It will be understood that my improvements may be embodied in various forms of construction and that the particular construction set forth above has been shown for purposes of explanation and illustration and is not intended to define the scope of the invention.

Vhat I claim is:

I. In an electric generator, the combination of a pair of stator pole pieces spaced apart and having opposite polar faces, a rotor operattively mounted between the pole pieces tp cooperate with the polar faces thereof and means for holding the pole pieces in if definite spaced relation to each other comprising rigid connecting members and screw devices adapted to exert thrust from one pole piece through said connecting members to the other pole piece.

2. In an electric generator, the combination of a pair of stator pole pieces spaced apart and having opposite polar faces, a rotor operatively mounted between the pole pieces to cooperate with the polar faces thereof, and means for holding the pole pieces in definite spaced relation to each other comprising straight bar permanent magnets and screw devices adapted to exert thrust from one pole piece through said magnets to the other pole piece.

3. In an electric generator, the combination of a pair of stator pole pieces spaced apart and having opposite polar faces, a pair of non-magnetic end plates secured to said pole pieces, a roller mounted between the polar faces of said pole pieces with bearing supports in the end plates, straight bar magnets arranged on opposite sides of the pole pieces with the positive poles of the magnets engaging one pole piece and their negative poles engaging the other pole piece, means carried by one of the pole pieces to receive end thrust of the magnets, and screws in the other pole piece arranged to engage the ends of the magnets and press them endwise against the said means.

4. In an electric generator, the combina tion of a pair of stator pole pieces spaced apart and having opposite polar faces, a pair of non-magnetic end plates secured to said pole pieces, a rotor mounted between the polar faces of said pole pieces with bearing supports in the end plates, one of said pole pieces being formed on opposite outer sides with magnet-engaging faces and adjacent under-cut shoulders and the other pole piece being similarly formed with magnet-engaging faces and adjacent flanges, straight bar magnets having their ends of onev polarity resting against the said shoulders and their opposite ends adjacent the said flanges, and screws mounted in said flanges to exert endwise pressure on the magnets, said magnets having their ends beveled so that the pressure of the screws forces the magnets laterally against the aforesaid lateral faces of the pole pieces.

In an electric generator, the combination of a combined base and pole piece, a top .pole piece spaced apart from the base pole piece, said pole pieces having opposite polar faces, a pair of non-magnetic end plates secured to said pole pieces, a rotor mounted between the polar faces of said pole pieces with bearing supports in the end plates, the base or bottom pole piece being formed on opposite outer sides with magnet-engaging faces and adjacent under-cut shoulders and the top pole piece being similarly formed with magnet-engaging faces and adjacent flanges, straight bar magnets having their ends of one polarity resting against the said shoulders and their opposite ends adjacent the said flanges, and screws mounted in said flanges to exert endwise pressure on the magnets, said magnets having their ends beveled so that the pressure of the screws forces the magnets laterally against the aforesaid lateral faces of the pole pieces.

6. In an electric generator, a pole piece, a permanent magnet arranged with one of its lateral pole faces against a face of the pole piece and formed with a beveled face ad j-acent said lateral pole face, and means for securing the magnet to the pole piece comprising an abutment for the magnet and a screw having its end engaging the said beveled face of the magnet and adapted by its pressure to clamp the magnet against the abutment and also press its lateral polar face against the face of the pole piece.

In testimony whereof, I hereunto aflix my signature.

F. J. WHITCOMB. 

